Disgraced NBA referee Tim Donaghy admitted in federal court in Brooklyn, N.Y., on Wednesday that he sold inside information to professional gamblers seeking to score on NBA games. Donaghy's plea of guilty to two felonies and the continuing investigation into gambling on NBA games raise numerous questions. Here are some of the questions and their answers:

What exactly has Donaghy admitted?

In court papers and in interviews with the FBI, Donaghy has admitted that he began gambling four years ago in violation of NBA rules. Although his plea in court Wednesday didn't include an admission that his bets during those four years included NBA games, the charges against him as outlined in court documents say that he did, and that he bet on games he officiated. He apparently did not do well on his bets. He admits that in December 2006, in an effort to supplement his income, he began delivering inside information on NBA players, referees and coaches to James ("Sheep") Battista, a professional gambler who attended the same high school (Cardinal O'Hara High in Springfield, Pa.) as Donaghy, although they were two years apart. When Donaghy's information proved to be correct and Battista won his bets, Donaghy collected $2,000. Donaghy's information must have been good because Battista soon started paying $5,000 for each winner.

What proof does the FBI have of Donaghy's chicanery?

Donaghy made literally hundreds of cell phone calls to place his bets and convey information to Battista. Most of the calls went to a Battista messenger, Thomas Martino. The FBI has the phone records of all three men and can show the pattern of calls just before games began and bets were placed. The evidence on Donaghy is similar to the phone records that proved Pete Rose was betting on baseball games when he managed the Reds in 1987 and that led to his lifetime ban from the sport. In addition to the phone records, the FBI can show cash payments made to Donaghy when his information led to winning bets.

Did Donaghy's gambling and his work for Battista affect the outcomes of NBA games?

Yes. Maybe not always by determining the winner and the loser, but the FBI agents who investigated Donaghy concluded that Donaghy "compromised [his] objectivity as a referee because of [his] personal financial interest in the outcome of NBA games." The actual effect may have been a change only in the point spread, but Donaghy easily could have gone far enough to turn a winner into a loser, or vice versa. As the investigation continues, we will know more about his calls and their effects on specific games.

What information did Donaghy provide to earn his $5,000 per game?

Court papers indicate that Donaghy told Battista the identities of the refs assigned to a game, described injuries, and analyzed "interactions between players" and "other personnel." The identity of the officiating crew is supposed to be kept secret until game time. But Donaghy, like all 60 NBA referees, knew the schedule and used it in his scheme. Injury information, especially at the last minute in games Donaghy officiated, could be especially advantageous to gamblers. Donaghy's insights on coaches and player rivalries, after 13 years in the league, also could be advantageous to gamblers.

How does an exchange of information about a basketball game become a federal crime?

The federal case against Donaghy is based on an arcane legal concept known as the "intangible right of honest services." Law professors and judges of higher courts have analyzed and debated "intangible rights" for decades, but in Donaghy's case, it means that the NBA was entitled to honesty and integrity from Donaghy in his work as a referee. Instead of honesty and integrity, the NBA has its worst scandal ever and the integrity of its product is under attack. To achieve his dishonest goals, court documents say, Donaghy made hundreds of cell phone calls, allowing the government to rely on the "intangible rights" concept and to charge him with wire fraud. And his dishonesty allowed the government to charge him with transferring gambling information across state lines, another federal crime. It's a serious set of charges, and Donaghy faces a possible 25 years in the penitentiary.

Donaghy faces 25 years in prison for a gambling scheme that lasted six months. Michael Vick is negotiating with authorities for a term of 18 months in the penitentiary in a dogfighting scheme that lasted for six years. Is NBA gambling that much worse than dogfighting?

Both are serious crimes. Donaghy does face a 25-year sentence, theoretically, but a prison term of that length is unlikely. The length of the potential term is the result of major changes in federal gambling laws. The changes were designed to destroy offshore sports gambling with Internet bookies. Donaghy is caught under the tough new law. But if he succeeds in assisting the government in its investigation of significant targets, he will be eligible for a lenient sentence. The NBA is likely to argue and lobby for a stiff prison term, but the final decision on Donaghy's time in jail will come from U.S. District Court Judge Carol Bagley Amon.

Vick faces charges under a new federal law that is aimed at dogfighting, but the penalties established by the legislation are significantly less than the penalties for gambling violations. It is a quirk in federal crime laws. Many would argue that dogfighting should result in penalties more severe than the penalties for gambling, especially when there is so much legal gambling in the U.S.

If Donaghy has already admitted everything, who is the FBI's target in this investigation?

Battista was betting big money. In the patois of sports gamblers, he is known as a "mover." He would move the big money around in small parcels, trying to avoid changing the spread with his bets. If Battista put all the money down in one place, he would move the odds against his bet. It appears from court papers that he was betting other people's money. Who are the other people? Are they the targets of this investigation? There is more to come.

What's next in this investigation?

It does not appear that any other NBA referees are involved. That could change, but it appears to be unlikely. Both Battista and Martino have been arrested and will soon appear in court. As federal agents and prosecutors continue to investigate, we will learn more about others involved in the scheme. Are mafia families involved? Rumors persist to that effect, but there is not yet any solid indication of crime syndicate involvement.

Lester Munson, a Chicago lawyer and journalist who has been reporting on investigative and legal issues in the sports industry for 18 years, is a senior writer for ESPN.com.